As service types of operators are increasing, to support better service experience, a service routing network needs to be deployed in a network, and a resilient service function chain (SFC) technology is put forward. This technology provides a basis for flexible service processing by linking multiple service processing functions. The SFC technology classifies service flows by using a service classifier (SCLA), and forwards the service flows to different service processing entities (SPE) by using a service forwarding entity (SFE) to perform service processing.
Refer to FIG. 1, which is a structural block diagram of a conventional service routing packet. As shown in FIG. 1, an SFC header (SFC Header, service header) is encapsulated in a packet entering a service routing domain.
The SFC Header includes information such as a path identifier (Path Id) and metadata (Metadata), and an SFE sends, according to the information, the packet to a corresponding SPE for processing. An Underlay (underlying/physical) network is responsible for forwarding of a service routing packet between SFEs.
However, a legacy SPE (Legacy SPE) does not support a packet carrying a service header. Therefore, in the prior art, when a packet is sent to a Legacy SPE, an SFC header needs to be stripped off before the SFE sends an original packet for processing. After finishing processing, the SPE sends a processed packet to the SFE. The SFE needs to add an original SFC header to the processed packet again before sending the packet to a next-hop device.
A problem in the prior art is that after an original packet is processed by a Legacy SPE, if a change occurs, an SFE cannot re-associate an SFC header that is stripped off from the original packet with a processed packet, and as a result, the SFC header of the packet cannot be restored. However, the SFC header includes information about a service function chain, and if the SFC header is lost, the packet abnormally interrupts processing of the service function chain to which the SPC header belongs.